<?php
// define array
$cities = array(
  "United Kingdom" => "London",
  "United States" => "Washington",
  "France" => "Paris",
  "India" => "Delhi",
  "Pak" => NULL
);

// search array for key
$a =  array_key_exists('India', $cities);
var_dump($a);

$b = isset($cities['India']);
var_dump($b);
echo "\n-------for PAK --------\n";
$a =  array_key_exists('Pak', $cities);
var_dump($a);

$b = isset($cities['Pak']);
var_dump($b);
